* Re: Hmmm... Stab at thinning scan_control
[not found] ` <20060119204411.18a83bd7.akpm@osdl.org>
@ 2006-02-04 0:29 ` Christoph Lameter
0 siblings, 0 replies; only message in thread
From: Christoph Lameter @ 2006-02-04 0:29 UTC (permalink / raw)
To: Andrew Morton; +Cc: Nick Piggin, linux-mm
On Thu, 19 Jan 2006, Andrew Morton wrote:
> Looks sane, although I don't have time to go through it at present - please
> send later.
Rediff against 2.6.16-rc2
Thin out scan_control: remove nr_to_scan and priority
Make nr_to_scan and priority a parameter instead of putting it into
scan control. This allows various small optimizations and IMHO makes
the code easier to read.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Index: linux-2.6.16-rc2/mm/vmscan.c
===================================================================
--- linux-2.6.16-rc2.orig/mm/vmscan.c 2006-02-02 22:03:08.000000000 -0800
+++ linux-2.6.16-rc2/mm/vmscan.c 2006-02-03 16:25:58.000000000 -0800
@@ -52,9 +52,6 @@ typedef enum {
} pageout_t;
struct scan_control {
- /* Ask refill_inactive_zone, or shrink_cache to scan this many pages */
- unsigned long nr_to_scan;
-
/* Incremented by the number of inactive pages that were scanned */
unsigned long nr_scanned;
@@ -63,9 +60,6 @@ struct scan_control {
unsigned long nr_mapped; /* From page_state */
- /* Ask shrink_caches, or shrink_zone to scan at this priority */
- unsigned int priority;
-
/* This context's GFP mask */
gfp_t gfp_mask;
@@ -1084,11 +1078,10 @@ static int isolate_lru_pages(int nr_to_s
/*
* shrink_cache() adds the number of pages reclaimed to sc->nr_reclaimed
*/
-static void shrink_cache(struct zone *zone, struct scan_control *sc)
+static void shrink_cache(int max_scan, struct zone *zone, struct scan_control *sc)
{
LIST_HEAD(page_list);
struct pagevec pvec;
- int max_scan = sc->nr_to_scan;
pagevec_init(&pvec, 1);
@@ -1164,12 +1157,11 @@ done:
* But we had to alter page->flags anyway.
*/
static void
-refill_inactive_zone(struct zone *zone, struct scan_control *sc)
+refill_inactive_zone(int nr_pages, struct zone *zone, struct scan_control *sc)
{
int pgmoved;
int pgdeactivate = 0;
int pgscanned;
- int nr_pages = sc->nr_to_scan;
LIST_HEAD(l_hold); /* The pages which were snipped off */
LIST_HEAD(l_inactive); /* Pages to go onto the inactive_list */
LIST_HEAD(l_active); /* Pages to go onto the active_list */
@@ -1296,10 +1288,11 @@ refill_inactive_zone(struct zone *zone,
* This is a basic per-zone page freer. Used by both kswapd and direct reclaim.
*/
static void
-shrink_zone(struct zone *zone, struct scan_control *sc)
+shrink_zone(int priority, struct zone *zone, struct scan_control *sc)
{
unsigned long nr_active;
unsigned long nr_inactive;
+ unsigned long nr_to_scan;
atomic_inc(&zone->reclaim_in_progress);
@@ -1307,14 +1300,14 @@ shrink_zone(struct zone *zone, struct sc
* Add one to `nr_to_scan' just to make sure that the kernel will
* slowly sift through the active list.
*/
- zone->nr_scan_active += (zone->nr_active >> sc->priority) + 1;
+ zone->nr_scan_active += (zone->nr_active >> priority) + 1;
nr_active = zone->nr_scan_active;
if (nr_active >= sc->swap_cluster_max)
zone->nr_scan_active = 0;
else
nr_active = 0;
- zone->nr_scan_inactive += (zone->nr_inactive >> sc->priority) + 1;
+ zone->nr_scan_inactive += (zone->nr_inactive >> priority) + 1;
nr_inactive = zone->nr_scan_inactive;
if (nr_inactive >= sc->swap_cluster_max)
zone->nr_scan_inactive = 0;
@@ -1323,17 +1316,17 @@ shrink_zone(struct zone *zone, struct sc
while (nr_active || nr_inactive) {
if (nr_active) {
- sc->nr_to_scan = min(nr_active,
+ nr_to_scan = min(nr_active,
(unsigned long)sc->swap_cluster_max);
- nr_active -= sc->nr_to_scan;
- refill_inactive_zone(zone, sc);
+ nr_active -= nr_to_scan;
+ refill_inactive_zone(nr_to_scan, zone, sc);
}
if (nr_inactive) {
- sc->nr_to_scan = min(nr_inactive,
+ nr_to_scan = min(nr_inactive,
(unsigned long)sc->swap_cluster_max);
- nr_inactive -= sc->nr_to_scan;
- shrink_cache(zone, sc);
+ nr_inactive -= nr_to_scan;
+ shrink_cache(nr_to_scan, zone, sc);
}
}
@@ -1359,7 +1352,7 @@ shrink_zone(struct zone *zone, struct sc
* scan then give up on it.
*/
static void
-shrink_caches(struct zone **zones, struct scan_control *sc)
+shrink_caches(int priority, struct zone **zones, struct scan_control *sc)
{
int i;
@@ -1372,14 +1365,14 @@ shrink_caches(struct zone **zones, struc
if (!cpuset_zone_allowed(zone, __GFP_HARDWALL))
continue;
- zone->temp_priority = sc->priority;
- if (zone->prev_priority > sc->priority)
- zone->prev_priority = sc->priority;
+ zone->temp_priority = priority;
+ if (zone->prev_priority > priority)
+ zone->prev_priority = priority;
- if (zone->all_unreclaimable && sc->priority != DEF_PRIORITY)
+ if (zone->all_unreclaimable && priority != DEF_PRIORITY)
continue; /* Let kswapd poll it */
- shrink_zone(zone, sc);
+ shrink_zone(priority, zone, sc);
}
}
@@ -1426,11 +1419,10 @@ int try_to_free_pages(struct zone **zone
sc.nr_mapped = read_page_state(nr_mapped);
sc.nr_scanned = 0;
sc.nr_reclaimed = 0;
- sc.priority = priority;
sc.swap_cluster_max = SWAP_CLUSTER_MAX;
if (!priority)
disable_swap_token();
- shrink_caches(zones, &sc);
+ shrink_caches(priority, zones, &sc);
shrink_slab(sc.nr_scanned, gfp_mask, lru_pages);
if (reclaim_state) {
sc.nr_reclaimed += reclaim_state->reclaimed_slab;
@@ -1593,10 +1585,9 @@ scan:
zone->prev_priority = priority;
sc.nr_scanned = 0;
sc.nr_reclaimed = 0;
- sc.priority = priority;
sc.swap_cluster_max = nr_pages? nr_pages : SWAP_CLUSTER_MAX;
atomic_inc(&zone->reclaim_in_progress);
- shrink_zone(zone, &sc);
+ shrink_zone(priority, zone, &sc);
atomic_dec(&zone->reclaim_in_progress);
reclaim_state->reclaimed_slab = 0;
nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL,
@@ -1852,6 +1843,7 @@ int zone_reclaim(struct zone *zone, gfp_
struct scan_control sc;
cpumask_t mask;
int node_id;
+ int priority;
if (time_before(jiffies,
zone->last_unsuccessful_zone_reclaim + zone_reclaim_interval))
@@ -1871,7 +1863,6 @@ int zone_reclaim(struct zone *zone, gfp_
sc.may_swap = !!(zone_reclaim_mode & RECLAIM_SWAP);
sc.nr_scanned = 0;
sc.nr_reclaimed = 0;
- sc.priority = ZONE_RECLAIM_PRIORITY + 1;
sc.nr_mapped = read_page_state(nr_mapped);
sc.gfp_mask = gfp_mask;
@@ -1892,11 +1883,11 @@ int zone_reclaim(struct zone *zone, gfp_
* Free memory by calling shrink zone with increasing priorities
* until we have enough memory freed.
*/
- do {
- sc.priority--;
- shrink_zone(zone, &sc);
+ for (priority = ZONE_RECLAIM_PRIORITY;
+ priority >=0 && sc.nr_reclaimed < nr_pages;
+ priority--)
+ shrink_zone(priority, zone, &sc);
- } while (sc.nr_reclaimed < nr_pages && sc.priority > 0);
if (sc.nr_reclaimed < nr_pages && (zone_reclaim_mode & RECLAIM_SLAB)) {
/*
--
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